Coaxial connector with means for preventing axial and rotational movement between connector components



Dec. 13, T966 J. H. BRYAN ET A1. 3,292,1'

COAXIAL CONNECTOR WITH MEANS PREVENTING AXIAL AND ROTATIONAL MOVEMENT BETWEEN CONNECTOR COMPONENTS Filed Oct. 23, 19 Sheets-Sheet l Dec. 13, 1966 J H. BRYAN ET Ax. 3,292,l17

COAXIAL CONNECTOR'WITH MEANS PREVENTING AXIAL ANI) ROTATIONAL MOVEMENT BETWEEN CONNECTOR COMPONEN," Filed 001,. 23, 1965 2 Sheu -Shee 21 United States Patent Office 3,292,117 Patented Dec. 13, 1966 3,292,117 COAXIAL CONNECTOR WITH MEANS FOR PRE- VENTING AXIAL AND ROTATIONAL MOVE- MENT BETWEEN CONNECTOR COMPONENTS John H. Bryant, Birmingham, and William A. Johnston,

Southfield, Mich., assignors to Omni Spectra, Incorporated, Southlield, Mich., a corporation of Michigan Filed Oct. 23, 1965, Ser. No. 507,633 19 Claims. (Cl. S33- 97) This is a continuation-in-part of the patent application of John H. Bryant et al., Serial No. 345,657, tiled February 18, 1964.

This invention relates to an improved coaxial connector construction,

An RF coaxial line consists of an inner conduc-tor, which is usually round but not necessarily so, a surrounding, usually coaxial, dielectric member, which is primarily 4to provide electrical insulation but which almost always lis to provide mechanical support for the center conductor as well, and an outer conductor, which has aninner surface which forms the boundary of the RF transmission line. The coaxial line then consists of three coaxial parts. When 'the coaxial line is in the form of a connector the means for mounting the connector is normally connected with the outer conductor and it is necessary to anchor the dielectric and the inner conductor to the outer conductor. When the coaxial line takes the form of a cable the three coaxial parts are firmly anchored by the frictional forces due to closeness of iit of these parts over a considerable length.

In practical use, it is necessary to terminate the ends yof coaxial cables either .to join a cable to a piece of equipment, a component, or to another cable. This is usually :accomplished `with littings or connectors located at the ends to be connected. `Connectors are thus normally used in mated pairs. To insure good electrical contact the metal parts (inner and outer conductors) must contact physically and usually one of the center conductors is Hprovided with some type of resilient, springlike gripping .ductors results in axial forces of considerable magnitude upon engagement and disengagement of mating connectors.

Frequently the dielectric is of a relatively smooth and frictionless material, such as Teflon, which, in a connector, does not frictionally grip the center conductor adequately to prevent axial movement -of the center conductor relative to the remainder of the connector kupon repeated engagement and disengagement with a mating connector; if the dielectric were not anchored, as by a combination of shoulders and snap rings, .it would be possible for the dielectric itself to shift relatively axially. Such 4a shift in the cen-ter conductor and/ or dielectric results in improper mating and orientation of components and hence causes electrical discontinuities resulting in unwanted reflections, etc.` Therefore `it is an object of the present invention to provide a coaxial -connector of the above described type in which the center conductor is held from axial movement relative to the outer conductor. It is another object of the present invention to provide a coaxial connector of the, above described type in which the cente'i` conductor and/or dielectric is held from axial movement relative to the outer conductor. It is a further, genera-l object of this invention to provide a coaxial connector of an improved construction.

There are means of restraining the center conductor which provide physical and electrical discontinuities thus impairing the performance of the connector. In the improved coaxial connector of the present invention the CFI center conductor is held from relative axial movement substantially Without causing electrical discontinuities and hence Without impairing the electrica-l characteristics of the connector. Therefore, it is still another object of this invention -to provide a coaxial connector of the above described type in which the center conductor is held from relative movement by a construction in which the electrical characteristics of the connector are substantially not impaired.

In the present invention the center conductor can also be held from rotation and hence loosening, etc. Therefore, it is another object of this invention to provide a coaxia-l connector of the above-described type in which the center conductor is held from both axial and rotational movement.

Other objects, features, and advantages ofthe present invention will become apparent from the subsequent description and the appended claims, taken in conjunction With the accompanying drawings, in which:

FIGURE l is a longitudinal, sectional view of a c0- axial connector having a male center conductor end portion and embodying features of the present invention;

FIGURE 2 is a sectional view taken substantially along vthe line 2-2;

FIGURE 3 is a fragmentary, longitudinal sectional view of a modification of a coaxial connector such as shown in FIGURES l and 2;

FIGURE 4 is a longitudinal sectional view of a coaxial connector having a female center conductor end portion 'and embodying features of the present invention;

generally .indicated by the numeral 10 and includes 'a hollow, metallic, tubular outer conductor member 12 having a central 'bore 13 of uniform diameter, a tubular, generally solid `dielectric core 14 located within and substantially filling the contines of the bore 13, and a metallic, solid, center conductor 16 located within a bore 18 extending coaxially through the core 14 and coaxially relative to the outer conductor 12. The dielectric core 14 can be made of a suitable material having good electrical, dielectric characteristics and in the preferred embodiment is made of a tetralluoroet'hylene iiuorocarbon resin, commonly known as Teflon.

The outer conductor l2 terminates at each end in a reduced section end portion 20 which in turn is ilush with the corresponding one of the ends of the core 14. The center conductor 1.6 is of a generally uniform crosssection and terminates at each end in a reduced section male end portion 22 which extends beyond the associated one of end portions 20 and which 4terminates in a generally conical tip. Each end of the outer conductor member 12 has a coupling nut 24 of conventional construction rotatably secured thereto via a snap ring 26 .located in an annular groove 28. Resilient, annular sealthe same time the coaxial cable connector would have a center conductor terminating in a cantilever, spring-like female construction (similar to end portion 22a of center conductor 16a in FIGURE 4) for engaging and grip-pingly receiving the reduced section male portion 22 of the center conductor 16. It can 'be seen that the engagement and disengagement of the coaxial cable connector with the connector results in substantial axial forces being exerted on the center conductor 16 as a result of the effort required to overcome the spring action of the mating center conductor. Unless provision is made, the center conductor 16 and possibly the core 14 can be displaced axially resulting in a discontinuity between mating parts and an impairment of the electrical characteristics of the connector 10. To prevent such axial movement, the center conductor 16 is secured to the outer conductor 12 in a manner to lbe presently seen.

The outer conductor 12 is provided with a diametrically extending through Ibore 32 intermediate its ends which is coaxially in communication with a diametrically extending bore 34 through the core 14. The center conductor 16 has a reduced diameter portion 36 which defines a pair of annular shoulders 40 and which is located in line with the opening defined by 'bores 32, 34. The latter opening with the portion 36 therein is filled -by a crosswise plug 38 of a material which is initially ilowa-ble and which later hardens to define a solid member. Hence the unfilled volume of the opening can |be easily completely lled by simply pouring the fluid material of the plug 38 therein. In order for the material of the lplug 38 to ow completely around the reduced diameter portion 36 the bore 34 in core 14 has a larger diameter than the portion 36; in the preferred form, the diameter of bore 34 is larger than the diameter of those portions of the center conductor 16 immediately adjacent to and on opposite sides of the portion 36. Preferably the length of the reduced section portion 36 is less than the diameter of the bore 34 in the core 14 such that the opposite shoulders 40 are engaged by the plug 38.

Note that in the above construction the center conductor 16 is fixed to the outer conductor 12 by means of the plug 38 and hence is prevented from moving axially relatively therewith upon engagement and disengagement with a mating connector. The core 14 is also similarly fixed to the outer conductor 12 and center conductor 16, thus eliminating the need to provide engaging shoulders and snap rings to -x the core 14 to the outer conductor 12.

The reduced section portion 36 presents an electrical discontinuity, i.e., change in impedance, to the RF wave being transmitted, such discontinuities adversely affect the transmission of an RF wave, i.e., causing unwanted reflections, etc. To substantially eliminate these adverse effects from connector 10, the plug 3'8 is made of a material having a higher dielectric constant than that of the core 14. Thus by properly selecting the diameter of the reduced diameter portion 36 relative to the difference in dielectric constants 'between that of the core 14 and of the plug 38 a substantially constant impedance can be provided over the length .of the electrical path of the connector 10.

In the preferred embodiment the plug 38 is made of an epoxy resin. Epoxies, in addition to having the desired high dielectric constant, also have excellent adhesion,

good viscosity characteristics, low shrinkage on cure and other favorable characteristics. Note that the epoxy plug 38 has a higherdielectric constant than the Teflon core 14.

To facilitate assembly, the bore 32 in outer conductor 12 is made prior to insertion of the core 14 and is of a lin FIGURE 3. t

FIGURE 4 depicts a modification of the connector 10 of FIGURES l and 2 in which components, etc. similar to those of connector 10 and serving similar functions are given the same number designation with the addition of a letter subscript. Thus in FIGURE 4 a connector 10a has a center conductor 16a terminating in female end portions 22a and has an outer conductor 12a terminating in externally threaded, male end portions 20a. Again, the outer conductor 12a, center conductor 16a, and dielectric core 14a are held together by a plug 38a. Note that the female end portions 22a have an aperture to receive an end portion (similar to end portion 22 of FIGURE l) and are slit longitudinally and crimped to restrict the opening and hence to resiliently grip the engaging male tip portion of a mating connector. In other respects, the connector 10a of FIGURE 4 is substantially identical to the connector 10` of FIGURES l and 2.

Looking now to FIGURE 5, a connector 10b is shown and has an outer shield or conductor 12b and an inner conductor 16ib and a dielectric core 14b. The center conductor 16b has a stepped construction having at its smallest diameter section a male end portion 22h with a coupling nut 24b located on the outer conductor 12b at that end. The opposite end is of an enlarged diameter and terminates in a female end portion 23. The center conductor 16b is provided with an annular groove 36h and a crosswise epoxy plug 38b extends through a diametrical bore 3411 in the dielectric core 14b and is in alignment with the annular groove 36h such that the plug 38b upon bein-g poured will flow through the aperture 34h and around the annular-groove 36h `and upon hardening will tightly secure the center conductor 1Gb and the dielectric core 14b together. The ydielectric core 14b is of a stepped construction with its enlanged end portion 47 being held between a washer member 49 and an insert member 51 with :both members 49 and 51 being a part of the outer conductor 12b. Thus with the connector 10b there is no need to secure the core member 14b to the outer conductor 12b, since it is already secured from axial movement by means of the construction shown and described.

Looking now to FIGURE 6, a different embodiment for a connector is shown. In FIGURE 6, a connector 10c is shown which is adapted to be mounted to one or more plates, such as plates 50 and 52. A center conductor member 16C is connected to the plates 50 and 52, and as shown in FIGURE 6 terminates in a male end portion. The outer conductor 12e is secured to plates 50, 52 by means of fasteners (not shown), through a flange portion 54. A dielectric core member 14c is located between the outer conductor 12C and the center conductor 16C and also extends into a pair of coaxial bores in plates 50 and 52 to insulate conductor 16C from plates 50 and 52. The outer conductor 12c is provided with an aperture 32C which is in line with a recess 34e in the core 14C. An epoxy plug 38C is located in the cavity defined by the aperture 32e and recess 34C to thereby lock the dielectric core 14e and outer conductor 12e together. In both embodiments shown in FIGURES 5 and 6, the dielectric material of the plugs 38b and 38a` and their sizes are selected such that substantially no electrical discontinuity is present between portions adjacent the plugs 38b and 38C, respectively, to the RF Wave being transmitted.

Thus with connectors constructed in accordance with the present invention, the center conductor is held from axial movement (and can also be held from rotation) relative to the outer conductor by means which do not impair the electrical impedancecharacteristics of the connector. In addition the central core which supports the center conductor is also fixed to the center and outer conductors, thereby eliminating the need for other mechanical means to ix the core. Other variations of the 'subject invention are those in which the center conductor is'held only to the dielectric core member or in which the dielectric core member is held to the outer conductor only or in which the center conductor, dielectric core member and outer conductor are all held together.

While it will be apparent that the preferred embodiments of the invention disclosed are well calculated to fulill the'objects above stated, it will be appreciated that the invention is susceptible to modification, variation and `change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a dielectric core member located within said outer conductor and extending for la substantial portion of the length of said outer conduc- -tor and having an axially extending bore, a center conductor supported by said dielectric core member within said bore, and means including a member different from lsaid center conductor, said outer conductor, and said core member and having a dielectric constant different than that of said core member and connected to and mechanically connecting together said center conductor, said outer conductor, and said core member for preventing relative axial movement therebetween in either axial direction and providing an electrical impedance to the RF wave substantially matching the electrical impedance of the electrical circuit of the coaxial connector immediately adjacent said means.

2. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a dielectric core meinber located within said outer conductor and having an axially extending bore, a center conductor located within said bore, a locking portion on said center conductor having a different cross-section than the adjacent portions of said center conductor and adapted to be held, plug means extending radially through said outer conductor and said core member and holding said locking portion for preventing relative axial movement between said outer conductor, said core member and said center conductor, said plug means having a diiierent dielectric constant than that of said core member, said different dielectric constant and said different cross-section selected to provide for the RF wave an electrical impedance along the length of said plug means substantially matching the impedance of that portion of the electrical circuit of the coaxial connector immediately adjacent said plug means.

3. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a dielectric core member located within said outer conductor and having an axially extending central bore, a center conductor located within said central bore and having a reduced section portion intermediate its ends, plug means extending radially through said outer conductor and said core member and engaging said reduced section portion of said center conductor for preventing relative axial movement between said outer conductor, said core member and said center conductor, said plug means having a higher dielectric constant than that of said core member, said higher dielectric constant and the cross-section of said reduced portion selected to provide for the RF wave an electrical impedance substantially matching the impedance of that portion of the electrical circuit of the coaxial con nector immediately adjacent said plug.

4. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a solid, dielectric core member located within said outer conductor and having an axially extending central bore, said outer conductor and said core member having a radially extending aperture, a center conductor located within said central bore and having a locking portion located within said aperture, a solid plug substantiallyl filling said aperture and holding said locking portion for preventing relative axial movement between said outer conductor, said core member and said center conductor, said plug having a diiierent dielectric constant than that of said core member, said locking portion having a dilerent cross-section than the adjacent portions of said center conduct-or and adapted to be held by said solid plug, said different dielectric constant and said diierent cross-section selected to provide for the RF wave an electrical impedance substantially matching the impedance of that portion of the electrical circuit of the coaxial connector immediately adjacent said plug means.

5. The coaxial connector of claim 4 in which said plug is formed from a material initially having a fluid state and is pourable into said aperture to deline, upon hardening, said solid core member.

6. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a solid dielectric core member located within said outer conductor and having an axially extending central bore, said outer conductor and said core member having an aperture defined by radially extending, coaxial bores through said outer conductor and said core member, a central conductor located within said central bore and having a reduced section portion located intermediate its ends and within said aperture, a solid plug substantially filling said aperture and engaging said reduced section portionof said center conductor for preventing relative axial movement between said outer conductor, said core member and said center conductor, said plug having a higher dielectric constant than that of said core member, said higher dielectric constant and the cross-section lof said reduced section portion selectedto provide for the RF wave an electrical impedance substantially matching the impedance of that portion of the electrical circuit of the coaxial connector immediately adjacent said plug.

7. The coaxial connector of claim 6 in which said core member is constructed of Teilen and in which said plug is constructed of an epoxy resin.

8. The coaxial connector of claim 6 in which the outer surface of said reduced section portion is roughened and in intimate engagement with said plug whereby rela-tive rotation of said center conductor is prevented.

9. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a solid dielectric core member located within said outer conductor and having an axially extending central bore, said outer conductor and said core member having an aperture defined by radially extending coaxial bores through said outer conduct-or and said core member, a center conductor located within said central bore and having a reduced section portion located intermediate its ends and within said aperture, and a solid plug substantially illing said aperture and engaging said reduced section portion of said center conductor for preventing relative axial movement between said outer conductor, said core member and said center conductor.

10. The coaxial connector of claim 9 with said aperture being of a greater diameter than said reduced section portion.

11. The coaxial connector of claim 9 with said aperture being lof a greater diameter than said center conductor and with the length of said reduced section portion being less than the diameter of said aperture.

12. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a solid dielectric core member located within said outer conductor and having an axially extending central bore, said outer conductor and said core member having a radially extending aperture, a center conductor located within said central bore and having a locking portion located within said aperture, a solid plug substantially lling said aperture and engaging said locking portion for preventing relative axial movement between said outer conductor, said core member and said center conductor.

13. In a high-frequency coaxial connector of the type having radially spaced inner and outer conductors and a dielectric filler between said conductors insulating the latter electrically from each other and physically supporting said inner conductor concentrically in said outer conductor, the improvement comprising: a plug disposed crosswise of said dielectric filler and interiitting with a 7. rst surface irregularity in said ller and a second surface irregularity in at le'ast one of-said conductors, said plug connecting said dielectric mechanically to said one of said conductors and preventing relative movement therebetween and also having a diierent dielectric constant than said ller which compensates for discontinuities in the electrical characteristics of the connector due to said surfaceI irregularities and provides an electrical impedance to the high-frequency wave at said surface irregularities substantially matching the electrical impedance of the connector adjacent said surface irregularities.

14. The apparatus of claim 13 in which said `one of said 4conductors is the inner conductor.

15. The apparatus of claim 13 in which said one of said conductors is the louter conductor.

16. The connector of claim 13 in which said dielectric filler is constructed of Teflon and in which said plug is constructed ofan epoxy resin.

17. The coaxial connector of claim 14 including means operatively connected with said plug and said inner conductor whereby said inner conductor is held from rotation.

18. A coaxial -connector for transmitting RF waves comprising: a tubular outer conductor, a solid dielectric core member located within said outer conductor and having an axially extending central bore, said core member having an aperture defined by a radially extending bore in saidcore member, a center conductor located within said central bore and having a reduced section portion located intermediate its ends and within said aperture, `and aisolid plug substantially filling said aperture and engaging said reduced section portion of said center conductor for preventing relative axial movement bctween said core member and said center conductor.

19. A coaxial connector for transmitting RF waves comprising: a tubular outer conductor, a solid dielectric -core member located within said outer conductor and having an axially extending central bore, said outer conductor and said core member having an aperture defined by radially extending coaxial bores through said. outer conductor and said core member, a center conductor located within said central bore, and a solid plug substantially lling said aperture for preventing relative axial movement between said outer conductor and said core member.

References Cited by the Examiner FOREIGN PATENTS l/l958 Germany. 8/ 1947 Great Britain.

Disclaimer 3,292,117.John H. Bryant, Birmingham, and William A. Johnston, Southfield, Mich. COAXIAL CONNECTOR WITH MEANS FOR PREVENTING AXIAL AND ROTATIONAL MOVEMENT BE- TVEEN CONNECTOR COMPONENTS. Patent dated Dec. 13, 1966. Disclaimer filed Aug. 8, 1977, by the assignee, Omni-Spectra,

Incorporated. Hereby enters this disclaimer to claims 13, 15, 16, 18 and 19 of said patent.

[yoz'al Gazette December 6', 1.977.] 

1. A COAXIAL CONNECTOR FOR TRANSMITTING RF WAVES COMPRISING: A TUBULAR OUTER CONDUCTOR, A DIELECTRIC CORE MEMBER LOCATED WITHIN SAID OUTER CONDUCTOR AND EXTENDING FOR A SUBSTANTIAL PORTION OF THE LENGTH OF SAID OUTER CONDUCTOR AND HAVING AN AXIALLY EXTENDING BORE, A CENTER CONDUCTOR SUPPORTED BY SAID DIELECTRIC CORE MEMBER WITHIN SAID BORE, AND MEANS INCLUDING A MEMBER DIFFERENT FROM SAID CENTER CONDUCTOR, SAID OUTER CONDUCTOR, AND SAID CORE MEMBER AND HAVING A DIELECTRIC CONSTANT DIFFERENT THAN THAT OF SAID CORE MEMBER AND CONNECTED TO AND MECHANICALLY CONNECTING TOGETHER SAID CENTER CONDUCTOR, SAID OUTER CONDUCTOR, AND SAID CORE MEMBER FOR PREVENTING RELATIVE AXIAL MOVEMENT THEREBETWEEN IN EITHER AXIAL DIRECTION AND PROVIDING AN ELECTRICAL IMPEDANCE TO THE RF WAVE SUBSTANTIALLY MATCHING THE ELECTRICAL IMPEDANCE OF THE ELECTRICAL CIRCUIT OF THE COAXIAL CONNECTOR IMMEDIATELY ADJACENT SAID MEANS. 